Spray nozzle and dental cleaning system

ABSTRACT

A dental cleaning system for providing a liquid jet for a mouth rinse includes a nozzle member, a nozzle attachment coupled to the nozzle member to define an axially extending chamber, a liquid duct configured to supply pressurized liquid to the chamber, a pressure piece disposed within the chamber, and a nozzle outlet extending out of the chamber and configured to discharge a cleaning jet.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 10/531,484 filedDec. 9, 2005.

TECHNICAL FIELD

This description relates to a mouth rinse, a spray nozzle and a dentalcleaning system according to the preamble of the independent claims.

BACKGROUND

It is known that the cleaning effect of oral rinses is improved by usingspecial spray nozzles to create liquid jets of a specific configuration.EP 0 841 038 A1 discloses an impeller which is arranged in the spraynozzle for rotation about its axis of rotation, being set in rotation bythe cleaning liquid that is fed to the impeller. The cleaning liquidpasses to the outlet through a duct which is arranged in the impeller atan angle to the axis of rotation. As the result of the rotation of theimpeller the cleaning liquid is discharged from the outlet of the spraynozzle in the form of a rotating liquid jet. A single jet is thuscreated and circulates, evenly distributed, on an expanding cone. Inspite of the enlarged effective area, the cleaning effect of a liquidjet created with such a spray nozzle is not optimal as yet. Inparticular the removal of marginal plaque is possible with such a spraynozzle only to an inadequate degree. Only non-adhering plaque can beremoved with the liquid jet of a mouth rinse. The removal of plaque inthe approximal region and in the gingival margin is possible only withhand toothbrushes, dental floss or electric toothbrushes, albeit to anunsatisfactory degree. Another disadvantage of the spray nozzle is therotating impeller, as moving components are subject to greater wear. Thelonger the use, the greater the wear, and this leads to an enlargementof the bearings, which in turn can result in a reduction of theimpeller's speed and ultimately its stoppage.

DE 199 59 188 A1 discloses a dental cleaning device similar to an oralrinse. In addition to a spray nozzle discharging a cleaning liquid, thedevice needs a cleaning scraper which is configured as a spoon-shapedauxiliary part. A pressure of 3 to 6 bar and an exit velocity of 5 m/sto 15 m/s are provided for the liquid. It is explained that highervalues should be avoided as otherwise the liquid jet is perceived asunpleasant. These values are said to be a good compromise between a highcleaning effect and an intensity of impact that is still perceived aspleasant. It is a disadvantage, however, that the scraper is unable toreach into all interproximal spaces and other regions of the teeth.

SUMMARY

According to one aspect, a mouth rinse and a spray nozzle for the mouthrinse which afford an improved cleaning effect. The liquid jet should becapable of removing firmly adhering plaque from the approximal regionand the gingival margin. The spray nozzle for creating such a liquid jetshould work as far as possible without suffering any wear and be ofsimple construction. Also, a device enabling extensive cleaning of theteeth and the gums should be provided for the spray nozzle.

According to another aspect, the cleaning liquid is fed at high pressureto a spray nozzle such that a liquid jet comprised of microsized dropsis discharged at high velocity from a nozzle outlet. In particular thenozzle outlet forms a thin, fast moving liquid film which is thentransformed into microsized drops moving at high velocity.

By providing for the pressure to amount to at least 15 bar and/or thevelocity to equal at least 23 m/s the cleaning effect is improvedcompared to the prior art.

A high pressure of at least 15 bar is sufficient to enable reliableformation of the microsized drops, with the velocity of the liquid jetbeing preferably higher than 25 m/s. However, a distinctly bettercleaning effect is achieved with a pressure of over 20 bar and/or avelocity of over 35 m/s.

In one or more embodiments of the dental cleaning device, it is possibleto dispense with a scraper or other auxiliary part. In particular themicrosize of the drops is perceived as relatively pleasant. However, insome embodiments, the mouth rinse can be used simultaneously incombination with a brush part or other auxiliary part which contacts theteeth directly. The auxiliary part can be constructed as a ring-shapedbrush which is arranged concentrically around the nozzle outlet.

The high impact energy of the drops on the plaque layer causes thecleaning liquid to be deflected sideways. The shear forces generated inthe process tear open the plaque surface, forming pits and craters. Asthe liquid jet is comprised of a multiplicity of drops, this process isrepeated in rapid succession. The plaque is thus removed layer by layer.The advantage of a liquid jet which is comprised of drops and created inthis manner is that plaque adhering in the approximal region and in thetooth-gingiva junction region can now be removed. Furthermore, onaccount of the mechanical removal of the plaque layer there is no needfor any additive in the cleaning liquid, thus making it possible to usewater as cleaning liquid for removing the plaque.

To produce the drops with high velocity the cleaning liquid is fed tothe spray nozzle at high pressure. Depending on the specialconfiguration the pressure lies at over 15 bar, approximately, inparticular between 25 bar and 55 bar, approximately, with the bestcleaning results being achievable in a pressure range from 35 bar to 45bar.

For the drops to be produced it is necessary for the cleaning liquid tobe atomized or sprayed. Particularly small drops can be created withidentical nozzle diameters and pressures when the liquid jet isconfigured as a diverging hollow cone jet. Another advantage of thediverging hollow cone jet is that the spray area becomes larger as thedistance from the nozzle outlet increases, thus enabling faster cleaningHowever, it is also conceivable to create a solid cone jet or a flat jetapart from the hollow cone jet.

The formation of the jet is decisive, along with the jet shape, for theconfiguration of the microsized drops. These drops can be created byforming the cleaning liquid in the nozzle outlet as a thin film which isevenly distributed over the inner wall of the nozzle outlet. On leavingthe nozzle outlet this evenly distributed film disintegrates shortlyafter the nozzle outlet into the microsized drops.

Adhering plaque layers can be removed particularly well with a liquidjet comprised of drops with a size of around 5 μm to 10 μm and avelocity of at least 23 m/s, preferably around 45 m/s to 55 m/s.

In one embodiment, the spray nozzle includes a chamber, a liquid ductextending into a chamber and supplying pressurized cleaning liquidthereto, and a nozzle outlet extending from the chamber for discharginga cleaning liquid jet. Advantageously, the chamber is connected to awhirl chamber of approximately round cross section for creating acirculating flow of the cleaning liquid, the nozzle outlet extendingcentrally from said whirl chamber and being comprised of a preferablyapproximately cylindrical narrow passage and an optionally adjacent, inparticular approximately conical, expansion. The expansion can also beomitted or be constructed with a non-conical shape as required.

With this construction it is possible to create a liquid jet comprisedof microsized drops with high velocity, which, owing to the velocity ofthe drops, is capable of removing dental plaque. A cleaning operationperformed with the spray nozzle constructed as a hollow cone nozzleenables in the same period of use a gentler cleaning operation than withan electric toothbrush on account of a distinctly reduced abrasion ofthe epithelial cell layer. Furthermore, after using an electrictoothbrush the spray nozzle of one embodiment provides an additionalreduction of approximately 60% plaque particularly in the approximalregion. The spray nozzle works without any moving parts, which would besubjected to intensive wear.

A narrow passage in the form of a bore with a diameter of approximately0 1 mm to 0.2 mm and a depth of approximately 0.05 mm to 0.2 mm hasproven to be advantageous for creating the microsized drops with highvelocity. A narrow passage of such construction ensures that thecleaning liquid discharged from the whirl chamber enters at highpressure and high velocity into the optionally succeeding expansion.

An expansion, in particular in the form of a cone or hollow cone, hasproven to be advantageous for finally forming the liquid jet comprisedof many drops, with the expansion following directly on the narrowpassage. This atomizer principle enables particularly fine drops to beproduced. After the cleaning liquid has passed through the narrowpassage it spreads over the wall of the hollow cone as an evenlydistributed thin film which rotates around the axis of symmetry of theexpansion on account of the whirl chamber. The high tangential velocitycauses the film to disintegrate into the microsized drops as soon as itexits from the hollow cone, in particular shortly after the nozzleoutlet. A cone or hollow cone with a length of approximately 0.2 mm to 05 mm and an opening angle of approximately 20° to 70° has proven to beadvantageous for an optimum configuration of the drops. This nozzlegeometry also distinguishes itself by enabling small volumetric flows,for example, of less than 80 ml/min, even at high drop velocities,without the nozzle geometry becoming so small that the costs ofproduction increase. Extremely small nozzle geometries, which also havea reduced service life, are thus avoided. Furthermore, the nozzleconstructed as a hollow cone has the advantage of displaying a verystable jet profile even in the presence of manufacturing inaccuracies orimpurities.

However, the use of a flat jet nozzle or a solid cone nozzle instead ofthe hollow cone nozzle may also be contemplated.

The outlet can be of compact and hence space-saving construction if itis formed in a nozzle attachment arranged on the nozzle member.

Further contributing to simplifying the production of the nozzleattachment is an arrangement of the narrow passage and the expansion ina separate component, for example, a nozzle plate. Fitting the nozzleplate in the nozzle attachment entails only little additional effort,while production is more favorable with regard to accuracy, dimensionalstability and costs. Furthermore, the nozzle plate can be made of adifferent material that is more resistant to wear.

Replaceability of the nozzle attachment can be configured to detachablyconnect to the nozzle member for ease of replacement, for example. Thedetachable connection can be constructed either as a screw connection oras a snap- and push-lock connection, for example, and can thus bereplaced, for example in case of damage. At the same time a nozzlemember constructed in this fashion enables the accommodation ofconventional nozzle attachments, which are operated with a substantiallylarger volumetric flow at considerably lower pressure.

Advantageously, the chamber includes a pressure piece in the spraynozzle to form a whirl chamber. The pressure piece is arranged in achamber which is formed between the nozzle attachment and the nozzlemember. To fix the pressure piece in the chamber, the part of thepressure piece located in the nozzle member or nozzle attachment isinserted with a press fit or is fixed by means of latching elementsarranged on the nozzle attachment or nozzle member. On the one hand thisfixing simplifies the mounting, on the other hand the pressure piece isheld captive on one of the two parts during any replacement of thenozzle attachment. However, it is also conceivable to hold the pressurepiece clamped between the nozzle member and the nozzle attachmentthrough oversize or by means of a spring.

The pressure piece can have a cup-shaped part at each of its ends. Thefirst cup-shaped part faces the narrow passage in the nozzle attachmentand forms with its interior space the whirl chamber. The secondcup-shaped part faces the liquid duct in the nozzle member.

In the first cup-shaped part provision is made for at least one openingthrough which the cleaning liquid is allowed to flow from the interiorspace of the first cup-shaped part into the chamber. A free outflow ofthe cleaning liquid is ensured when the interior space of the cup-shapedpart is in communication with the chamber through at least one openingbut preferably through three to four openings.

If the openings are constructed as axial slits through the cup-shapedpart, the sections of the cup-shaped part lying between the slits formspring arms which assist the fixing of the pressure piece.

The function of the spring arms is assisted when the pressure piece ismade of an elastic material, e.g., a plastics material.

The arrangement of the whirl chamber in the pressure piece as a separatecomponent guarantees a particularly simple production. The whirl chamberis formed by the interior space in the first cup-shaped part, which ismounted on the area around the narrow passage, the narrow passageforming the outlet from the whirl chamber. To seal the whirl chamber,the cup-shaped part is seated around the narrow passage. In oneembodiment, the cup-shaped part has a planar seating surface. This typeof sealing prevents deformations in the pressure piece. Suchdeformations could occur with a line-shaped sealing arrangement when thecup-shaped part seals with an edge.

Furthermore it would also be conceivable to construct the sealing facesas a cone. In this construction, the cone angles of the nozzle plate andthe pressure piece are configured to be exactly in agreement. Bycontrast, two plane surfaces afford greater economy of manufacture.

It is also possible to provide, in the area around the narrow passage,detent hooks which cooperate with notches on the outer circumference ofthe pressure piece in order to ensure the sealing effect. This fixingaffords the added advantage of holding the pressure piece captive in thenozzle attachment during a replacement of the spray nozzle.

The access to the whirl chamber is provided by at least one opening inthe first cup-shaped part, which opening is perpendicular or at an anglesmaller than about 90° to the axis of symmetry of the pressure piece.The configuration of the jet has been shown to be influenced by thenumber, the cross section and the position of the openings. Good resultswere obtained with two opposite lying openings which are constructed asslits.

To create a sufficient whirl in the whirl chamber, the openings leadinto the whirl chamber approximately transverse to and centrally offsetfrom the longitudinal axis of the whirl chamber. The magnitude of thecenter offset and the angle at which the openings lead into the whirlchamber are likewise decisive for the jet configuration. For example, acenter offset big enough for the liquid jet discharged from the openingsto impact on the opposite lying wall of the whirl chamber at an anglesmaller than about 45° has proven to be favorable. In this angular rangethe jet is able to transfer its energy to the developing whirl mosteffectively.

Feeding the cleaning liquid to the openings takes place through groovesin the first cup-shaped part which extend parallel to the axis ofsymmetry of the pressure piece. This type of feeding avoids radialfeeding, which would require a large space for construction. The spraynozzle can thus be constructed with a small diameter.

A pressure piece with two cup-shaped parts is advantageous when theliquid duct is coaxial with the narrow passage. A spray nozzle with asmaller axial dimension can be achieved when the liquid duct is alignedapproximately radially to the narrow passage. With this construction thearea facing the liquid duct can be dispensed with, thus simplifying thedesign of the pressure piece.

On a device including a pump adapted to be driven by an electric motorand a liquid container, in which the pump is connected to a spray nozzleby means of a tube and a hand piece, a spray nozzle according to any oneof the device claims is arranged preferably on the hand piece.

If the spray nozzle is arranged on the hand piece of the device so as tobe exchangeable for another nozzle, then the device can be operated invarious operating modes. The replaceability permits the use of not onlythe high-pressure spray nozzle for the removal of dental plaque butalso, for example, a conventional jet and/or spray nozzle. The spraynozzle is operated with a small volumetric flow at a high pressure, anda standard mouth rinse nozzle with a large volumetric flow at a lowpressure. If both nozzles are operated with approximately the samehydraulic power, the pump can be driven by one electric motor, with thepump being of the switchable type using, for example, a switchable geartrain.

Switching between the operating modes can take place without additionaleffort or devices in the hand piece when the nozzle attachment is usedfor detection of the operating mode to be set. Depending on the nozzleattachment used, a defined pressure builds up in the device. In thiscase a pressure sensor can be arranged between the pump and the spraynozzle in order to detect the pressure of the cleaning liquid conveyedto the spray nozzle, with a signal indicative of the detected pressurebeing deliverable from the pressure sensor to a control unit and theelectric motor being controllable by the control unit with the operatingmode assigned to the detected pressure.

In another construction use is made of the fact that, unlike aconventional jet and/or spray nozzle used in mouth rinse mode, thehigh-pressure mode with the spray nozzle produces a high torque and alow rotational speed. In this case a rotational speed or torque sensorcan be arranged on the pump or on the electric motor in order to detectthe rotational speed or the torque of a rotor of the pump or theelectric motor, and a signal indicative of the detected rotational speedor the detected torque can be delivered from the rotational speed ortorque sensor to a control unit, and the electric motor and/or the pumpand/or the gear train can be controlled by the control unit with theoperating mode assigned to the detected rotational speed or the detectedtorque. It will be understood, of course, that the torque and/or therotational speed can also be detected by means of a measurement taken ofthe electric current consumed by the motor. In conclusion it can be saidthat switching between operating modes is possible by detecting thepressure or the electric current.

Particularly advantageous further developments of the mouth rinse bymeans of which the mouth rinse can be switched over from a firstoperating mode to a second operating mode with lower pressure, will beexplained in the following. Provision is herein made for an eccentricshaft or a crankpin to be adjustably arranged in their total eccentricdimension on a drive element, with a crank mechanism being provided fora pump of the mouth rinse, and the mouth rinse being provided with adrive element adapted to be driven for rotation about an axis ofrotation by a drive device, and with an eccentric shaft or crankpin,which acts as an output and is arranged on the drive element a totaleccentric dimension away from and parallel to the axis of rotation.

As the result of the adjustable total eccentric dimension the output onthe crankpin has at least two movements. With these movements it ispossible to operate the plunger of a pump with at least two differentstrokes. In this manner the pump supplies a small delivery volume with asmall stroke, while with a large stroke it supplies a large deliveryvolume. Adjustment takes place by reversal of the drive's direction ofrotation.

If the drive element is adapted to be driven for rotation in reversiblemanner and if the eccentric shaft is arranged on an output element whichis arranged on the drive element such as to be freely pivotal between afirst and a second end position about a pivot axis arranged a firsteccentricity away from and parallel to the axis of rotation, then theadjustment of the eccentricity as the result of a reversal of thedirection of rotation on the drive shaft distinguishes itself by aparticularly small mechanical effort, whereby the space requirements forthe eccentric drive are not substantially increased. No additionallocking of the set total eccentric dimension is necessary as theeccentricity depends solely on the direction of rotation. The advantageof this type of adjustment is that the adjustment can take place underload, for example, of the pump. An additional adjusting unit orintervention from the outside to change the eccentricity is notrequired. The eccentric drive is characterized furthermore by littlewear, as the components are moved toward each other only when switchingover between the eccentricities, with the switching over usually takingplace under no-load conditions.

Setting the eccentricity dependent on the direction of rotation of thedrive shaft is particularly easy when the output element has a disk thatis mounted on the drive element such as to be pivotal about the pivotaxis, when the disk carries a crankpin that extends with a secondeccentricity parallel to the pivot axis, and when the drive element hasan axially projecting driver that is pivotal with the drive element andprojects between two stops defining the two end positions, the stopsbeing arranged on the disk. The driver rests against the respective stopdepending on the direction of rotation. The rotation of the diskrelative to the drive element depending on the direction of rotationcauses the total eccentric dimension of the crankpin relative to thedrive element to increase or decrease. By selectively choosing theangular position of the two stops relative to each other it is possibleto achieve practically any ratio of small to large total eccentricdimension.

The eccentricities of the disk and the crankpin are likewise variablewithin wide limits, with the eccentricity of the disk being desirablysmaller than that of the crankpin. This ensures that the disk alwaysrests against the driver.

A maximum and a minimum total eccentric dimension of the crankpinrelative to the axis of rotation of the drive element is obtainable witha crank mechanism when the stops are arranged such that theeccentricities of the disk and the crankpin are added to or subtractedfrom each other. The angular distance between the stops on the diskequals 180° in this case. Any variation of the angular position of oneor both distances leads to a decrease or increase of one or both totaleccentric dimensions depending on the stop changed.

The stops in the disk can be constructed in the form of at least onecircular-arc-shaped, concentric groove in which the driver is movable.The ends of the groove then form the stops for the driver in therespective direction of rotation. The groove extends preferably over anangular range of up to 180° and can fully penetrate the disk or beconstructed to only a defined depth of the disk.

It is also possible for two or more symmetrically arranged grooves ofthis type to be constructed in the disk, with a driver being movablyarranged in each groove so as to produce a symmetrical support load.

Producing the stops becomes simpler and more economical when they arearranged as regions of the disk with a larger radius.

A particularly good guidance of the disk is achieved by the arrangementof two symmetrically arranged drivers which cooperate with stops thatare arranged likewise symmetrically on the disk. Skewing of the disk dueto a tilting moment is effectively prevented by the symmetricalengagement. The bending moments and torques as well as the transverseforces from the output-end loading of the crankpin are supported by thestops and/or the disk.

The drivers can be produced particularly easily and hence economicallywhen they are integrally formed on the drive element as studs.

However, it is also possible for the drivers to be arranged as separatecomponents in the form of bolts on the drive element. This configurationhas the advantage of the drivers being replaceable.

In another construction, either the stops or the drivers are of theadjustable type. The adjustability can be dependent on the torque, forexample. For this purpose the stops are equipped with a spring againstwhich the drivers rest. Depending on the magnitude of the torquegenerated by the drive device, the stops are displaced by the driversalong the spring travel, thus resulting in a change of the eccentricity.In this way it is possible, in combination with suitable throttling ofthe conveyed liquid, to fine-tune or individually adapt the stroke ofthe pump piston, which is produced in dependence upon the direction ofrotation, and hence the volumetric flows and pressures. As the result ofthe dependence on the torque it is possible to set the stroke using acontroller of the drive device.

However, it is also conceivable to configure the drivers to beadjustable by means of a spring and to move them against fixed stops.

The spring is, in the simplest case, a spring that is arranged at therespective end of the groove or on the driver. The adjustability can bevaried in accordance with the spring characteristic of the spring used.

Helical springs which enable a large spring travel have proven to befavorable for the adjustability within relatively wide limits Disksprings, leg springs or leaf springs are advantageous for large torquesor small spring travels.

The disk is mounted for rotation on the drive element by means of a boltwhich is constructed as a separate component. The mounting of the boltcan be dispensed with, however, when it is integrally formed either onthe disk or on the drive element.

For mounting the disk the drive element is disk-shaped at one end. Thedisk is carried in this disk-shaped region. This construction isparticularly favorable when the drive element is an injection-moldedplastics part.

By configuring the disk-shaped region as a separate component it ispossible to provide switchable eccentric drives which are adaptable tovarious requirements with regard to the volumetric flow and, whereapplicable, pressure of the liquid to be conveyed. The correspondingdisk-shaped region for the requirement has to be mounted, thedisk-shaped regions differing solely in the eccentricity of the bearingof the disk and accordingly arranged drivers.

The disk-shaped region can be equipped with several mounts for the diskand accordingly arranged mounts for the drivers, the mounts of the diskhaving different eccentricities than the drive element. Hence it ispossible, with one disk-shaped region and the accordingly selectedbearing for the disk, to adapt the eccentric drive or crank mechanism tothe respective requirements, thus reducing the diversity of parts.

The drive element can be driven by a drive device via a gear train. Agear is fastened to the drive element for this purpose. The arrangementof the gear on the drive element is easily constructed when the gear isconnected to the drive element in one integral piece, preferably byplastic injection molding, or when it forms the drive element.Furthermore, the use of plastic leads to a reduction in the weight ofthe eccentric drive.

Further contributing to simplifying the drive element is the integrationof the disk-shaped region with the bearing of the disk and the driversin a drive gear, particularly a spur gear of the drive element.

The crank mechanism is of compact construction which can be variedaccording to requirement. For an axially short design the crankmechanism is disk-shaped, whereas in cylinder design it builds to smallradial dimensions. Simple and hence economically produced elements areused when disk- or cylinder-shaped components are employed.

Setting of the total eccentric dimension between the crankpin and thedrive element as a function of the direction of rotation of the driveelement is achieved in accordance with a second embodiment by a crankpinwhich is part of a crankshaft eccentrically and rotatably mountedrelative to the drive element and by a driver which is arranged on thedrive element and limits the turning of the crankshaft relative to thedrive element. The eccentricity of the crankpin on the crankshaft isthus superimposed upon the eccentricity derived from the arrangement ofthe crankshaft relative to the drive element. By turning the crankshaftrelative to the drive shaft it is possible to change the eccentricity ofthe crankpin relative to the drive shaft. Turning of the crankshaftrelative to the drive element takes place with each change of thedirection of rotation on the drive element, the crankshaft only beingable to turn relative to the drive element within the limits of thedriver.

The eccentricities resulting from the arrangement of the crankshaftrelative to the drive element and from the configuration of the crankpinon the crankshaft are variable within wide limits, with the eccentricityof the crankshaft relative to the drive element being preferably smallerthan that of the crankpin. It is thereby ensured that the crank webinvariably rests against the driver.

The eccentricities arising as the result of the direction of rotationare determined by the arrangement of the driver on the drive element. Ina particularly simple construction the driver is a radially extendingbar which acts on the crank web of the crankshaft.

The arrangement of the driver is particularly simple to construct whenit is integrally formed on the drive element.

A maximum and a minimum total eccentric dimension of the crankpinrelative to the drive element are achieved when the crank web is drivenby the driver in a radially outward pointing position and a radiallyinward pointing position. In this arrangement the two positions and thebearing of the crankshaft are on one line. The driver is arrangedlikewise with a nearly radial orientation.

If the eccentricity of the crankshaft is greater than the radius of thedrive element caused by the acting forces and moments, the bearings ofthe crankshaft lie alongside the drive element. Therefore, the driveelement and the crankshaft have to be joined together in suitable mannerThe unbalance of the drive element produced thereby is avoided when theradius of the drive element is selected large enough for the bearing ofthe crankshaft to lie inside this radius.

Advantageously, a piston of a pump of the mouth rinse can be axiallyslidably and guided in two relatively spaced bearings of the pumphousing.

Hence the bearings inside the pump housing are positioned toward thepiston ends. The shortening of the regions of the piston projectingbeyond the bearings achieved thereby leads to a reduction of the staticand dynamic loads on the bearings and the piston on account of the nowsmaller transverse forces acting on the piston ends.

A further reduction of the loads in the bearings is achieved when atleast one of the bearings is arranged in an end region of thedisplacement path of the piston in the pump housing. This enables forthis particular bearing the moments to be reduced practically to zero,thus limiting the loads to the action of forces. Particularly littleexpenditure is involved when the pump chamber is constructed as thebearing site. It is also conceivable to implement the bearing on thepiston end of a sliding-block guideway. For this purpose the pumphousing is expanded so that preferably the cover faces of thesliding-block guideway are accommodated by the housing. The bearing isconstructed in accordance with FIG. 23 such that it fully accommodatesthe cover faces of the sliding-block guideway as the piston end, thebearing having an axial dimension that is larger than the stroke of thepiston. It is thus guaranteed that the cover faces of the sliding-blockguideway are invariably in the area of the bearing.

A large bearing receiving the cover faces of the sliding-block guidewayis avoided when the sliding-block guideway is not arranged at the end ofthe piston but, as shown in FIG. 24, between the two ends of the piston.In this way it is possible to obtain a bearing which is substantiallysmaller in diameter. Any unfavorable bearing forces which may arisedepending on the application are negligible.

The crankpin can be mounted for rotation in a sliding block which ismovably arranged in a direction transverse to the direction of movementof the piston in a sliding-block guideway connected to the piston.

Mounting the crankpin in a sliding block with bore ensures on the onehand a relatively fast and extensive connection of the moved crankpin toanother component. In this way the high surface pressure of the crankpinagainst another component is reduced. In spite of the still largerelative movement between the sliding-block guideway and the slidingblock, the surface pressure against the piston is substantially reducedon account of the very large surface compared to a crankpin, which has apositive effect on the service life of the components concerned.Furthermore, the loads of other components, particularly those of thebearing sites of the piston and the seal, are also reduced.

With the smaller friction forces and friction moments it is possible toreduce the motor power, thus reducing the current input to the pump orenabling a smaller motor to be used. Also, the reduced load permits thecrankpin to be constructed with a smaller diameter, which contributeslikewise to reducing the friction. On the other hand the planar supportenables greater force transmission, which means that such a pump can bedesigned to accommodate higher pressures.

A reduction of the load is also achieved by fabricating the slidingblock and the sliding-block guideway from a material pair with lowfriction.

A further reduction of the surface pressures is achieved by providingfor a cardan coupling between the piston and the crankpin. It is thuspossible to compensate in particular for production-induced orassembly-induced tolerances and/or deformations which lead to aspatially skewed arrangement of the crankpin relative to the piston.

A particularly simple construction of the cardan or cardan-typearrangement is accomplished when the sliding block has a cylindricalcross section and the sliding-block guideway is constructed as a borewith a corresponding cross section in a part formed fast with the pistonsuch that the sliding block is arranged to rotate about its ownlongitudinal axis. This movability permits the movement about one axisto be compensated for. Another essential advantage of the cylindricalsliding block is that the entire outer surface of the sliding block isin contact with the sliding-block guideway. This configurationdistinguishes itself by an extremely low surface pressure. Thecomponents have a long life on account of the low specific loads.

Like the cylindrical sliding block, the piston is also mounted forrotation about its longitudinal axis. This enables the sliding-blockguideway to perform a compensation movement about a second axis. Hencethe interaction of movements by the sliding block and the sliding-blockguideway guarantees a compensation of movement about two axes, which isnecessary for compensating for the tolerances of a spatially skewedcrankpin.

Additional friction between the crankpin and the sliding-block guidewayis avoided when an elongated hole is constructed in the wall of thesliding-block guideway for the crankpin to pass through, said elongatedhole having a greater width than the diameter of the crankpin. With anelongated hole constructed like this, unwelcome friction is avoidedparticularly with a spatially skewed crankpin.

To further reduce the friction between the crankpin and the slidingblock it is suitable to mount the crankpin for rotation in the slidingblock in a bearing which is inserted in a bore of the sliding block. Thebearing is constructed preferably as a sliding bearing. Through asuitable choice of material the friction can be reduced still further.In addition to cast or wrought alloys, plastics are an advantage inparticular when the requirements are not too high. Plastics have goodsliding and antifrictional properties and are characterized by goodlubrication.

The eccentric drive or crank mechanism can have a drive shaft, and theeccentricity of the crankpin relative to the drive shaft of theeccentric drive can be adjustable. This construction enables thecrankpin to be switched over to another eccentricity with which adifferent piston stroke can be achieved. This enables the pump to beused in two operating modes.

The pump inlet and/or the pump outlet can be arranged axially to thelongitudinal dimension of the pump chamber.

However, it is also possible for the pump inlet and/or the pump outletto be arranged radially to the pump chamber, whereby they can bearranged radially one beside the other.

It is also possible, however, for the pump inlet and pump outlet to bearranged axially one behind the other.

When in this case the piston or the wall of the pump chamber has alongitudinal groove or flattening through which at least one of theports is connected to the pump chamber, then this ensures a connectionof the ports to the pump chamber independently of the position of thepiston.

Non-return valves arranged in the ports make sure that the pump inletand pump outlet are closed depending on the movement of the piston.

The seal can be arranged between the bearings of the piston such that itradially encloses the piston. The direct ingress of wear particles isgreatly reduced by this decoupling of bearing and seal. This leads to amaterial reduction of wear on the seal. The smaller amount of wearprolongs the life of the seal without any accompanying pressurereduction in the pump chamber.

The seal is subjected to particularly small loads when it is arrangedcentrally between the bearings. Particularly with an off-center positionof the sliding block relative to the piston axis, the seal is exposed toonly minor radial loads by tilting moments.

A further reduction in the ingress of wear particles from the bearingsis achieved when in the region between the bearings the piston has alarger or a smaller diameter than in the area of the bearings.

In one embodiment, the seal is fixed in the pump housing and includes asealing lip which radially encloses the piston and is in sealingengagement with it.

A weakening of the piston diameter by a circumferential groove is thusavoided. This construction enables the piston to be dimensioned with asmaller diameter because of the absence of the circumferential groove.This enables a reduction in the required space and in the masses movedin oscillating fashion.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a spray nozzle illustrating a firstembodiment;

FIG. 2 is a view of the nozzle plate of FIG. 1 on an enlarged scale;

FIG. 3 is a perspective view of the pressure piece of FIG. 1;

FIG. 4 is a top plan view of the whirl chamber of FIG. 1;

FIG. 5 is a sectional view of a spray nozzle illustrating a secondembodiment;

FIG. 6 is a sectional view of a spray nozzle illustrating a thirdembodiment;

FIG. 7 is a view of a device with a spray nozzle;

FIG. 8 is a sectional view of a first embodiment of an eccentric driveor crank mechanism of the mouth rinse, taken in the plane I-I of FIG. 9;

FIG. 9 is a sectional view of the eccentric drive, taken in the planeII-II of FIG. 8;

FIG. 10 is a view of the eccentric drive of FIG. 8 with the direction ofrotation changed, taken in the plane IV-IV of FIG. 11;

FIG. 11 is a sectional view of the eccentric drive, taken in the planeIII-III of FIG. 10;

FIG. 12 is a perspective view of the eccentric drive similar to FIG. 8with two drivers;

FIG. 13 are views of a spur gear and a disk of the eccentric drive;

FIG. 14 is a view of a crank mechanism with variable stops;

FIG. 15 is a sectional view of a second embodiment of an eccentric driveor crank mechanism, taken in the plane VIII-VIII of FIG. 16;

FIG. 16 is a sectional view of the eccentric drive, taken in the planeIX-IX of FIG. 15;

FIG. 17 is a sectional view of the eccentric drive of FIG. 15 with thedirection of rotation changed, taken in the plane X-X of FIG. 18;

FIG. 18 is a sectional view of the eccentric drive, taken in the planeXI-XI of FIG. 17;

FIG. 19 is a perspective view of a plunger pump illustrating a firstembodiment;

FIG. 20 is a sectional view of the plunger pump of FIG. 19;

FIG. 21 is a sectional view of the plunger pump of FIG. 19 in the areaof the eccentric drive;

FIG. 22 is a sectional view of a second embodiment of a plunger pump inthe region of the pump chamber, with the arrangement of piston and crankbeing exchanged compared to FIG. 19;

FIG. 23 is a schematic part-sectional view of an embodiment of thearrangement of a possible bearing;

FIG. 24 is a schematic part-sectional view of another embodiment of thearrangement of a possible bearing;

FIG. 25 is another view of a spray nozzle;

FIG. 26 is a view of segments of a tooth;

FIG. 27 is a view of a drop as it impinges on plaque;

FIG. 28 is a view as in FIG. 27, but at a later instant;

FIG. 29 is a view as in FIG. 28, but upon plaque removal;

FIG. 30 is a perspective view of a spray nozzle;

FIG. 31 is a perspective view of a spray nozzle illustrating anotherembodiment;

FIG. 32 is a perspective view of a spray nozzle illustrating a stillfurther embodiment;

FIG. 33 is a side view of a brush element; and

FIG. 34 is a front view of the brush element.

DETAILED DESCRIPTION

The spray nozzle 1 shown in FIG. 1 is comprised of a nozzle member 2which is connected to a nozzle attachment 3 by means of a screwconnection 4. Arranged in the nozzle member 2 is a liquid duct 5 for thecleaning liquid.

The nozzle member 2 combines with the nozzle attachment 3 to form achamber 6 into which the liquid duct 5 leads. Inserted in this chamber 6is a pressure piece 7.

The pressure piece 7 is constructed to be radially expanded andcup-shaped at its two ends. With the first cup-shaped part 8 thepressure piece 7 sits on a nozzle plate 9. The second cup-shaped part 10encompasses the area in which the liquid duct 5 leads into the chamber6.

The second cup-shaped part 10 has four evenly distributed axial slits 11through which cleaning liquid conveyed in the liquid duct 5 is allowedto flow into the chamber 6.

The first cup-shaped part 8 has two grooves 12 formed axially on thecircumference of the pressure piece 7. In the area of the grooves 12 thecup-shaped part 8 is encompassed by a ring 13. This ring 13, which canbe made of polyamide in one example, seals off the circumference of thecup-shaped part 8 such that the grooves 12 act as ducts. Adjoining thelower end of the grooves 12 and extending radially thereto are ducts 14formed as slits which extend approximately tangentially into a whirlchamber 15.

The whirl chamber 15 is formed by the space in the interior of the firstcup-shaped part 8 and by the nozzle plate 9. At the same time, thenozzle plate 9 closes an opening 16 in the nozzle attachment 3.

The nozzle plate 9 in turn has a passage 17 through which the cleaningliquid exits the whirl chamber 15.

In FIG. 2 the passage 17 of the nozzle plate 9 is shown on an enlargedscale. The passage is comprised of a bore 18 which forms the outlet fromthe whirl chamber 15. The bore 18 has a diameter of, for example, 0.15mm and a length of, for example, 0.11 mm.

Adjoining the bore 18 is a diverging hollow cone 19. The hollow cone 19has an opening angle of, for example, 30° at a length of, for example,0.35 mm.

The cleaning liquid set in rotation in the whirl chamber 15 by theapproximately tangential ducts 14 is greatly accelerated in a whirlingpattern as the result of the small diameter of the bore 18. The cleaningliquid then enters the hollow cone 19. In the hollow cone 19 thecleaning liquid develops an evenly distributed film over the wall of thehollow cone 19 as the result of the whirling movement and thedecompression. At the same time the film rotates about the axis A athigh velocity. When the thus moving cleaning liquid reaches the edge 20,the film disintegrates into a multiplicity of drops with an average sizeof around 10 μm, which move with a velocity of around 50 m/s. Theaggregate of the drops disperses from the edge 20 to form asubstantially conical pattern.

The pressure piece 7 in FIG. 3 shows the two cup-shaped parts 8, 10. Thesecond cup-shaped part 10 is divided into four sections by four slits 11which are evenly distributed around the circumference. On account oftheir form these sections act as spring arms 21. The spring arms 21 bearagainst the nozzle member 2 such that the first cup-shaped part 8 isurged with the face 22 against the nozzle plate 9.

Arranged on the circumference of the first cup-shaped part 8 are the twogrooves 12. The grooves 12 are each adjoined by a duct 14, which leadapproximately tangentially straight into the whirl chamber 15. Throughthe grooves 12 and the ducts 14 the cleaning liquid flows from thechamber 6 to the whirl chamber 15.

The position of the ducts 14 in relation to the whirl chamber 15 becomesapparent from FIG. 4. The ducts 14, rather than leading radially fromthe grooves 12 to the center, extend in opposite directions in parallelwith each other, entering the whirl chamber 15 with a center offset X.The center offset is selected such that a jet entering the whirl chamber15 without interference impacts on the wall of the whirl chamber at anangle smaller than 45° and is diverted on the wall into a circulatingcurrent.

FIGS. 5 and 6 show a second embodiment of the spray nozzle 1. The nozzlemember 2 is arranged, in relation to the axis of symmetry of the nozzleattachment 3, not radially but preferably approximately tangentially onthe nozzle attachment 3. Hence the liquid duct 5 leads into the chamber6 likewise from the side. The chamber 6 is closed with a cover 23.

The pressure piece 7 is simplified inasmuch as no second cup-shaped partis necessary. The whirl chamber 15 is arranged again in the firstcup-shaped part 8. In FIG. 5 the pressure piece 7 takes support upon thecover 23 such that the face 22 rests with a sealing effect on the nozzleattachment 3. In FIG. 6 the sealing effect of the face 22 is assisted bya spring 24 which urges the pressure piece 7 against the nozzleattachment 3.

The cleaning liquid again reaches the whirl chamber 15 through grooves12 and slits 14 which are arranged similar to FIGS. 1 to 4. In contrastto FIG. 1 the spray nozzles 1 of FIGS. 5 and 6 have no nozzle plate. Thebore 18 and the hollow cone 19 are arranged in the nozzle attachment 3.Provided on the nozzle attachment 3 are several extensions 25 formedaround the exiting jet. The extensions 25 have an axial dimension of 3mm, approximately. The extensions 25 are used for setting an optimumworking distance in that the spray nozzle 1 is placed with theextensions 25 on the regions to be cleaned.

The device 26 of FIG. 7 includes a liquid container 27 which can befilled with cleaning liquid by the user. The cleaning liquid is conveyedout of this liquid container 27 through a tube 30 to a hand piece 31 bymeans of a pump 28 which is powered by an electric motor 29. The spraynozzle 1 is replaceably arranged on the hand piece 31. Arranged on theelectric motor 29 is a sensor 32 which measures the torque generated bythe electric motor 29 and then sends a signal to the pump 28 so that thelatter can be operated in the operating mode which corresponds to thespray nozzle used.

In use the pump 28 generates in high-pressure mode a volumetric flow of50 ml/min at approximately 40 bar. This is roughly equivalent to amechanical or hydraulic output of 2,000 ml/min bar, approximately, or3.3 W, approximately. When a conventional spray nozzle is arranged onthe hand piece 31, the sensor 32 detects the changed torque comparedwith the spray nozzle 1 and the pump 28 is operated in mouth rinse mode.In this case the pump 28 delivers a volumetric flow of 300 ml/min,approximately, with a pressure of 6 bar. This results in a mechanical orhydraulic output of 1,800 ml/min bar, approximately, or 3.0 W. With themechanical output in both operating modes being approximately equal, itis possible to operate the device 26 with a pump 28 and an electricmotor 29.

Description of Crank Operation for the Mouth Rinse

The eccentric drive described in the following has at least twodifferent movements at the output. The different movements at the outputcan be set with minimum expenditure. Adjustment is possible furthermorewithout any outside intervention in the drive. The space required forthe eccentric drive is not significantly larger.

The eccentric drive 101 of FIG. 8 has a drive element 102 which isconstructed as a drive shaft and carried in two bearings 103, 104.Fastened to one end of the drive shaft is a spur gear 105. The spur gear105 is connected to a drive device, not shown, and is used for drivingthe drive shaft. A disk-shaped region 116 for receiving a disk 106 isintegrated in the spur gear 105. For this purpose the spur gear 105 hasa bore 107 arranged with an eccentricity e1. The disk 106 is rotatablymounted in the bore 107 with a pin 108. The disk 106 has a bore 109arranged with an eccentricity e2, in which is inserted a crankpin 110acting as an output device. Acting on the crankpin 110 is a connectingrod 111 which drives the piston, not shown, of a pump. The disk 106 hasa groove 112 which is engaged by a driver 113 constructed as a bolt thatis fastened in the spur gear 105.

In the representation shown in FIG. 8, the disk 106 and the crankpin 110are arranged such that the eccentricities e1 and e2 of the disk and ofthe crankpin, respectively, are oriented in a line. In this position theeccentricities e1 and e2 add up to the largest total eccentric dimensione3. The crankpin 110 transfers to the connecting rod 111 a stroke equalto twice the total eccentric dimension e3.

FIG. 9 shows the spur gear 105 with the disk 106 arranged eccentricallyon it and the crankpin 110 arranged eccentrically to the disk 106. Thedriver 113 fastened to the spur gear 105 engages in thecircular-arc-shaped groove 112 of the disk 106. The groove 112 extendsover an arc of 180°. The ends 114, 115 form the stops for the driver113. The largest total eccentric dimension e3 is obtained when the spurgear 105 is driven in the shown direction of rotation. The driver 113runs in the groove 112 of the disk 106 as far as the stop 114. When thedriver 13 abuts the stop 114, the disk 106 rotates in the direction ofrotation shown, and with it the crankpin 110 with the spur gear 105.

FIGS. 10 and 11 show a changed position of the crank mechanism 101 ofFIGS. 8 and 9, the spur gear 105 being driven in the opposite directionof rotation. On its end close to the disk 106, the drive shaft has adisk-shaped region 116 designed to receive the disk 106. The spur gear105 is arranged on the circumference of the disk-shaped region 116.

Upon switching over to the direction of rotation shown, the connectingrod 111 counteracts with a braking moment such that the crankpin 110 andhence the disk 106 persist in their position. The driver 113 arranged inthe spur gear 105 now runs from the stop 114 in the groove 112 to thestop 115 such that the spur gear 105 rotates through an angle of 180°relative to the disk 106. As soon as the driver 113 abuts the stop 115,the disk 106 is driven along by the driver 113. The spur gear 105 andthe disk 106 rotate again at the same rotational frequency.

As the result of the spur gear 105 rotating through an angle of 180°relative to the disk 106, the eccentricity e2 of the crankpin 110 actsagainst the eccentricity e1 of the disk 106. The smallest totaleccentric dimension e4 is obtained. The crankpin 110 now only transfersto the connecting rod 111 a stroke that is equal to twice the smallesttotal eccentric dimension e4.

The crank mechanism 101 of FIG. 12 shows an eccentric drive 101 that isslightly different compared to FIG. 8, with the toothed ring of the spurgear 105 being illustrated as a dot-and-dash line. The spur gear 105 hastwo symmetrically arranged drivers 113 which run in two concentricallyarranged circular-arc-shaped grooves 112 in the disk 106. The ends ofthe grooves 114, 115 form the stops for the drivers 113.

The eccentric drive 101 shown in FIG. 13 has a spur gear 105 whosetoothed ring is shown as a dot-and-dash line. The spur gear 105 hasseveral bores 117, 117′, 117″. These bores 117, 117′, 117″ serve tomount the disk 106, with the bores 117, 117′, 117″ having differenteccentricities e1, e1′, e1″. Hence the spur gear 105 can be used forvarious requirements by mounting the disk 106 in the corresponding bore117, 117′, 117″. Associated with the bores 117, 117′, 117″ arecorresponding bores 118, 118′, 118″ in which the driver 113 is arranged.

The disk 106 again has stops 114′, 115′ which however are not arrangedin the disk 106 as grooves 112 but as regions 119 with a larger radiuson the circumference of the disk 106.

The disk 106 of FIG. 14 has two concentrically arranged grooves 112 inwhich two drivers 113 run. One helical spring 120 is arrangedrespectively at the ends of the grooves 112 such that depending on thedirection of rotation of the drive shaft each driver 113 rests against ahelical spring 120 and the disk 106 rotates at the rotational frequencyof the drive shaft. The helical springs 120 have the effect ofpreventing the drivers 113 from resting against the very end of therespective groove 112. Therefore, the crankpin 110 no longer lies on aline with the center of the disk 106 and the drive shaft, and theeccentricity e1 is added only in part to the eccentricity e1 of the disk106. The resulting largest total eccentric dimension e3 is thus smaller.In addition, shocks upon changing the direction of rotation arecushioned.

The helical springs 120 are constructed with regard to their springcharacteristic such that even minor changes of the torque generated bythe drive device are sufficient to change the spring travel by way ofthe drivers 113 transmitting the torque. With changes of the springtravel the disk 106 turns relative to the drive shaft, thus producingminor changes in the position of the crankpin 110 and hence in the totaleccentric dimension e3, e4. With a torque controller on the drive deviceor the drive shaft it is thus possible to finely adjust the totaleccentric dimension e3, e4 and hence the stroke of the connecting rod.

In a second embodiment of the eccentric drive 101 of FIG. 15 the spurgear 105 and the drive shaft are a single-piece construction forming adrive element 102. The drive shaft is rotatably mounted in the bearings103, 104. The drive shaft has a bore 121 carrying a crankshaft 122. Thecrankshaft 122 is arranged with an eccentricity e1 in the drive shaft.The crankpin 110, which is connected by way of a crank web 123 to thecrankshaft 122, has an eccentricity e2 relative to the crankshaft 122.Fastened to the crankpin 110 is the connecting rod 111.

In the presentation shown, the crankshaft 122 is arranged such that thecrankpin 110 is orientated in a radially outward direction relative tothe bearing of the crankshaft 122. In this position the eccentricitiese1, e2 of the crankshaft 122 and the crankpin 110 add up to the maximumtotal eccentric dimension e3. The crankpin 110 transfers to theconnecting rod 111 a stroke equal to twice the total eccentric dimensione3.

In the sectional view of the eccentric drive 101 of FIG. 16 the driveelement 102 is driven in the direction of rotation shown by the drivedevice, not shown, via the spur gear 105. A driver 113 integrally formedon the drive element 102 is arranged such that it entrains thecrankshaft 122 in the position shown in FIG. 15.

FIGS. 17 and 18 show the arrangement of the eccentric drive 101 of FIGS.15 and 16, the spur gear 105 being driven in the opposite direction ofrotation. Upon changing the direction of rotation, the crankshaft 122rotatably arranged in the drive shaft rotates through 180°. The crankpin110 is arranged in a radially inward direction relative to the bearingof the crankshaft 122 such that its eccentricity e2 is now orientated inopposition to the eccentricity e1 of the crankshaft 122. The smallesttotal eccentric dimension e4 is thus obtained between the crankpin 110and the drive element 102. The crankpin 110 transfers to the connectingrod 111 a stroke equal to twice the smallest total eccentric dimensione4.

At this point it should be noted, in particular with reference to FIGS.10, 11, 17, 18, that the sub-eccentricities are not shown to scale inmagnitude and direction. It is preferred rather to provide for beingable to select the eccentricity e2 larger than the eccentricity e1. Thismeans that when the small eccentric dimension e4 is set, then thedrive-end driver 113 rests against the stop 115 in every position ofrotation.

Such a crank mechanism can be used not only for mouth rinses but canalso be applied to other fields including, for example, pump devices ingeneral or devices on which a rotary movement is to be converted into atranslational movement.

Description of the Plunger Pump of the Mouth Rinse

The mouth rinse has a plunger pump. This pump displays a better degreeof efficiency compared to known mouth rinse pumps. In particular theplunger pump should have a drive for the piston that is as low wearingas possible. Also, the life of the piston and the seal should beincreased.

The plunger pump 201 of FIG. 19 has a pump housing 202 with an axiallyarranged pump inlet 203 and a radially arranged pump outlet 204. At theopposite end of the plunger pump 201 a piston 205 extends through thepump housing 202. The piston 205 is driven by an eccentric drive 206 orcrank mechanism. The piston 205 has a sliding-block guideway 207 whichreceives a sliding block 208. To move the piston 205 a drive shaft 209of the eccentric drive 206 or crank mechanism is set in rotation by anelectric motor not shown.

The inner architecture of the plunger pump 201 with the pump chamber 210is shown in FIG. 20. The pump chamber 210 has, with pump inlet 203 andpump outlet 204, two ports, with a non-return valve 211 associated witheach. The one or several non-return valves 211 can be of thespring-loaded type. The non-return valves 211 are configured such thatwhen the piston 205 moves out of the pump chamber 210 the non-returnvalve 211 in the pump inlet 203 opens while the non-return valve 211 inthe pump outlet 204 is closed. During this movement of the piston 205,liquid is drawn from a container, not shown, in the mouth rinse, throughthe pump inlet 203 and into the pump chamber 210. When the piston 205moves in the opposite direction, the action of the non-return valves 211is reversed and the liquid is conveyed through the pump outlet 204 to ahand piece, not shown, of the mouth rinse.

The piston 205 is mounted in two bearings 212, 213 that are situated inthe pump housing 202. In addition to being axially movable, the piston205 is also arranged to be rotatable about its longitudinal axis H. Thebearing 212 on the pump chamber 210 is constructed such that the pistonend 214 is guided during a stroke between top and bottom dead center.The bearing 213 is situated at the other end of the pump housing 202. Aseal 215 is fixedly arranged in the pump housing 202 centrally betweenthe two bearings 212, 213. In this arrangement a sealing lip 216 sealsoff the piston 205. Arranged at the other end of the piston 205 is thesliding-block guideway 207. The sliding-block guideway 207 has a bore217 in which the cylindrical sliding block 208 is arranged.

The slider or sliding block 208 is both axially movable as well asrotatable about the axis V. Owing to the rotary arrangement of thepiston 205 and the slider or sliding block 208 about the axes H and V,the piston 205 is connected to a crankpin 220 of the eccentric drive 206(or the crankpin 110 of the eccentric drive 101) in a practicallycardan-type fashion, the only difference being that the piston 205rotates about the axis H instead of being pivoted about an axisperpendicular to the two axes H and V. The piston 205 and this cardan orcardan-type connection enables a spatially skewed arrangement of thecrankpin 220, which occurs as the result of tolerances or elastic and/orplastic or other deformations, to be compensated for.

A cardan connection in the sense of this description results when thepiston 205 and the sliding block are rotatable and pivotal,respectively, about different axes H, V, with the two axes H and Vextending perpendicular to each other.

The sliding block 208 has a bore 218 that extends transverse to the axisV and in which a bearing bushing 219 is inserted. The bearing bushing219 is designed to receive the crankpin 220. For it to be received inthe sliding block 208 the crankpin 220 has to penetrate thesliding-block guideway 207. For this purpose the sliding-block guideway207 has an elongated hole 221. The width of the elongated hole 221 islarger than the crankpin diameter. Contact of the crankpin 220 with thesliding-block guideway 207 is thus ruled out. The width is selected suchthat no contact takes place even with a spatially skewed arrangement ofthe crankpin 220.

To drive the piston 205 the crankpin 220 moves on a circular path. Inthe presentation shown the crankpin 220 and the sliding block 208 are attop dead center. By contrast, the piston 205 lies exactly centrallybetween its two reversing points which limit its stroke. During amovement of the crankpin 220 in clockwise direction, the sliding block208 moves downward in the sliding-block guideway 207 during the firsthalf rotation. After a quarter rotation of the crankpin 220 the piston205 reaches its rear reversing point which terminates the intakeoperation. Up to this moment the non-return valve 211 in the pump inlet203 is open while the other non-return valve 211 is closed. During thesecond quarter rotation of the crankpin 220 the piston 205 moves againin the direction of the pump chamber 210. The non-return valve 211 inthe pump inlet 203 is closed while the non-return valve 211 in the pumpoutlet 204 is open. After a half rotation the crankpin 220 mounted inthe sliding block 208 reaches bottom dead center. The piston 205 is inthe position shown. During the second half rotation of the crankpin 220the sliding block 208 is again moved up, whereby after half of thismovement the piston 205 reaches its front reversing point whichterminates the discharge operation. It should be noted that springs forbiasing the non-return valves 211 are not shown in FIG. 20.

FIG. 21 shows the crank mechanism 206 with the sliding-block guideway207 of the piston 205. The crank mechanism 206 has a drive shaft 209 towhich a disk 222 is fastened. The disk 222 carries the crankpin 220which is arranged with the eccentricity E1. The crankpin 220 reachesthrough the elongated hole 221 of the sliding-block guideway 207 andinto the sliding block 208 where it is received in a bearing bushing219.

The plunger pump 201 of a second embodiment in FIG. 22 shows thearrangement of the pump outlet 204 behind the pump inlet 203, both portsbeing radially arranged on the circumference of the plunger pump 201.The ports 203, 204 are integrated in a pressure piece 223 which ismounted on the plunger pump 201. The piston 205 has a flattening 224 onits side close to the pump inlet 203 and the pump outlet 204. Theflattening 224 guarantees a communication of the pump outlet 204 withthe pump chamber 210 which is independent of the position of the piston205. In this embodiment, both non-return valves 211 are loaded or biasedby a respective spring.

The piston 205 has three regions with different diameters 225-227, thediameters increasing from the bearing 212 through the region of the seal215 to the bearing 213 which is no longer shown. With these steps225-227 of piston diameter, any wear particles which arise are preventedfrom being distributed into the regions of the seal or the bearings.

Such a pump can be used not only in every mouth rinse but also in otherfields including, for example, irrigation systems. It can be usedbasically in all pump devices with piston guidance.

Other Aspects of the Cleaning Process and of the Mouth Rinse

The mouth rinse preferably has two functions (operating modes) or twodifferent, optionally usable spray nozzles. One function serves as aconventional mouth rinse with a low pressure of preferably around 4 to 8bar, particularly around 6 bar (high-pressure function=around 45 bar).In this case microsized drops (spray function) are formed. The velocityof the discharged cleaning liquid is low. (This velocity lies preferablybelow 20 m/s, particularly in the range from 10 m/s to 15 m/s.) The flowrate with this mouth rinse function equals at least 100 ml/min,particularly 200 ml/min to 400 ml/min, preferably around 300 ml/min Theother high-pressure function was already described in detail.

The different functions are enabled by the switchable eccentric deviceor two variously long stroke travels of the pump.

One of the two functions can be optionally set. One function ispractically a mouth rinse function, the other a new special function forthe removal of dental plaque which can be compared with cleaning teethusing a toothbrush or has a comparable cleaning effect. This specialfunction can at least reduce the use of a toothbrush and thus avoidsevere abrasion.

The special function can also exist in an independent apparatus withouta mouth rise function. A station with two such different mouth rinses,i.e., one mouth rinse with low pressure (as one apparatus) and onehigh-pressure mouth rinse as another apparatus, is also conceivable,whereby both apparatuses can use the same or different pumps.

In the special function (high-pressure spray mode) provision is madepreferably for a high-pressure piston pump which reaches preferably amaximum of around 50 to 70 bar, particularly around 60 bar. One of theabove described pressure ranges is also possible. The flow rate equalspreferably around 50 to 70 ml/min, particularly 60 ml/min. The workingdistance between tooth and nozzle outlet equals around 2-6 mm Thesevalues have proven themselves in particular in clinical studies.

Such a dual-function system enables particularly effective dental care.While the teeth are cleaned of coarse particles of dirt and the bloodsupply to the gums stimulated with the actual mouth rinse, subsequentcleaning with the high-pressure spray nozzle ensures that the teeth arethoroughly cleaned. The system can also include an electric toothbrush.

FIG. 25 illustrates once again the spray function or the special spraynozzle. The arrow 300 designates the eccentrically arranged slits whichcreate the water whirl. The arrow 301 points to the whirl chamber withrotating water. The arrow 302 points to the rotating water which forms athin water film along the conical nozzle outlet. The water film (arrow303) is transformed into microsized drops at the exit.

The size of the drops can be changed by the geometry of the slits and/orthe distance of the slits from the middle of the whirl chamber and/or bythe angle and/or length of the outlet cone.

FIG. 26 shows the segments of a tooth according to “Rustogi”. After justtwo minutes of cleaning time per dentition with the mouth rinse, morethan 70% to 80% of the plaque is removed in the approximal regions (Dand F) and in the gingival margins (A, B and C). In the other regions(I, G, H and E) there is an even better cleaning effect. Cleaning alsooccurs in the proximal regions (spaces between the teeth). In this casethe cleaning causes very little abrasion, being very gentle on theteeth.

FIGS. 27 to 29 show the cleaning process with reference to a microsizeddrop 310. This drop impacts in pulse-like manner with high energy on aplaque layer 311 on a tooth 312 (FIG. 27). This energy causes the plaqueto be forced outward (FIG. 28), whereby a high pressure prevails in themiddle of the drop. A crater develops. The pressure shifts outward, asis illustrated by the two upward pointing arrows of FIG. 29.

FIGS. 30 to 32 show further embodiments of the spray nozzle which areadapted to be combined with the features of one or several of the abovedescribed nozzles.

The spray nozzle of FIG. 30 produces a flat, expanding jet. FIG. 31shows a spray nozzle with a solid cone jet. FIG. 32 shows a spray nozzlewith a hollow cone jet, with which a very gentle cleaning effect can beachieved, the volume of water being small.

FIGS. 33 and 34 show a spray nozzle with a nozzle attachment that isconstructed preferably as a ring-shaped brush 320—comprising preferablya plastic ring 321 and bristles 322 arranged in sectors. Said nozzleattachment can be fixedly or releasably arranged on the nozzle head.Apart from enhancing the cleaning effect the ring-shaped brush has theadded effect of a spacer element such that a defined (safety) distanceexists between the tooth and the nozzle opening. Also conceivable is afunction by which the ring-shaped brush rotates, being in particulardriven in alternating fashion in two directions of rotation similar toan electric toothbrush, e.g., by means of an electric drive,particularly a motor drive. However, other movement sequences and brushforms are also possible. A brushless element can also serve as a spacerelement. The brush-type nozzle attachment can also be used for a knownlow-pressure mouth rinse.

It will be understood that the dental cleaning system is not limited tothe examples described. Any combination of the individual features ofthe various examples is possible. In particular the combination of amouth rinse according to FIGS. 1 to 7 with an eccentric drive accordingto FIGS. 8 to 18 and/or with a pump according to FIGS. 19 to 24 issuitable.

All documents cited herein are in relevant part, incorporated byreference. The citation of any document is not to be construed as anadmission that it is prior art with respect to the present invention.

1. A dental cleaning system comprising: a spray nozzle; a nozzle member;a nozzle attachment coupled to the nozzle member to define an axiallyextending chamber; a liquid duct configured to supply pressurized liquidto the chamber; a pressure piece disposed within the chamber; a nozzleoutlet extending out of the chamber and configured to discharge acleaning jet; a hand piece to support the spray nozzle; a pump adaptedto be driven by an electric motor and disposed within the hand piece andconnected to the liquid duct by a delivery tube; and a storage reservoirin fluid communication with the liquid duct.
 2. The system of claim 1wherein the spray nozzle is detachably connected to the hand piece, thehand piece being configured to receive a plurality of spray nozzles. 3.The system of claim 2 wherein the pump is switchable between multiplemodes of operation depending upon the spray nozzle connected to the handpiece.
 4. The system of claim 2 further comprising: a sensor to detectan operating parameter of the motor; and a control unit configured toreceive the operating parameter detected by the sensor; wherein theelectric motor is controllable by the control unit as a function of anoperating mode assigned to the detected operating parameter.
 5. Thesystem of claim 4 further comprising at least two operating modes,including a high-pressure mode for the removal of dental plaque and areduced-pressure mode for an oral rinse.
 6. The system of claim 4wherein the operating parameter comprises rotational speed.
 7. Thesystem of claim 4 wherein the operating parameter comprises torque. 8.The system of claim 4 further comprising a pressure sensor disposedbetween the pump and the spray nozzle for detecting the pressure of thecleaning liquid fed to the spray nozzle, wherein the control unit isconfigured to receive a signal indicative of the detected pressure fromthe pressure sensor and the electric motor is controllable by thecontrol unit as a function of the operating mode assigned to thedetected pressure.
 9. The system of claim 1 further comprising a crankmechanism, the crank mechanism comprising: a drive device; a driveelement adapted to be driven for rotation about an axis of rotation bythe drive device; and an eccentric shaft adjustably arranged on thedrive element a total eccentric dimension away from and parallel to theaxis of rotation.
 10. The system of claim 9 wherein the drive element isadapted to be driven for rotation in reversible manner and the eccentricshaft is arranged on an output element which is arranged on the driveelement so as to be freely pivotal between a first and a second endposition about a pivot axis arranged a first eccentricity away from andparallel to the axis of rotation.
 11. The system of claim 10 wherein theoutput element comprises a disk that is mounted on the drive element soas to be pivotal about the pivot axis, the disk carries a crankpin thatextends with a second eccentricity parallel to the axis of rotation, andthe drive element comprises an axially projecting driver that is pivotalwith the drive element and projects between two stops defining the twoend positions along the disk.
 12. The system of claim 11 wherein thesecond eccentricity of the crankpin is greater than the firsteccentricity of the disk.
 13. The system of claim 11 wherein the firsteccentricity of the crankshaft is smaller than the second eccentricityof the crankpin.
 14. The system of claim 11 wherein the stops comprisearcuate concentrically arranged grooves in the disk in which the driveris movable, the grooves extending preferably over an angular range of upto about 180°.
 15. The system of claim 9 wherein the drive shaft isoperably connected to a drive gear.
 16. The system of claim 9 furthercomprising: a plunger pump including a pump housing and a pump chamber,the pump chamber including a pump inlet and a pump outlet; a pistonmovably guided in the pump chamber and sealed against the wall of thepump chamber by a seal; and an eccentric drive mechanism to drive thepiston, wherein the eccentric drive mechanism is operably connected tothe piston through a crankpin extending in a direction transverse to thedirection of movement of the piston, the piston being slidably guided intwo spaced bearings of the pump housing.
 17. The system of claim 16wherein at least one of the bearings is disposed in an end area of thedisplacement travel of the piston in the pump housing.
 18. The system ofclaim 16 wherein the crankpin is mounted for rotation in asliding-block, the sliding-block being movably arranged in a directiontransverse to the direction of movement of the piston along asliding-block guideway connected to the piston.
 19. The system of claim18 wherein the sliding-block has a cylindrical cross section and thesliding-block guideway is constructed as a bore with a portion of thecorresponding cross section being formed fast with the piston.
 20. Thesystem of claim 19 wherein a wall of the sliding-block guidewaycomprises an elongated hole for the crankpin to pass through, theelongated hole having a greater width than the diameter of the crankpin.21. The system of claim 20 wherein the crankpin is configured to rotatealong the slider in a bearing which is inserted in a bore of the sliderand the piston configured to rotate about its longitudinal axis and theslider is configured to rotate about its longitudinal axis.
 22. A dentalcleaning system, the system comprising: a spray nozzle; a nozzle member;a nozzle attachment coupled to the nozzle member to define an axiallyextending chamber; a liquid duct configured to supply pressurized liquidto the chamber; a pressure piece disposed within the chamber; a nozzleoutlet extending out of the chamber and configured to discharge acleaning jet; and a brush attachment connected to the spray nozzle. 23.The dental cleaning system of claim 22 wherein the brush attachment issubstantially ring-shaped.